Electronic housings or enclosures typically include card guides on opposed spaced apart walls into which a printed circuit boards, or similar cards, can be slidably mounted and supported to form various electronic apparatus. Most typically, such card guides have elongated bodies with inwardly facing channels that are mounted in pairs inside the equipment housing and slidably receive the printed circuit boards. On an outwardly facing side of the card guide, barbed posts have previously been provided that can be urged into openings or holes in the housing so as to secure the card guides to the housing.
FIG. 1 illustrates a typical prior art card guide and housing assembly. As shown in FIG. 1, an elongated card guide, generally designated 21, is shown mounted to a housing wall member 22 by a post 23 which extends through an opening 24 in housing wall 22. As will be seen, guide 21 generally has a C-shaped transverse cross section defining a channel or guideway 26 dimensioned to receive an edge 30 of a printed circuit board or similar electronic card 32. Post 23 will be formed with a barbed or laterally projecting or enlarged head 27, which can be urged through opening 24 with the barb snaps in behind the back surface of housing wall 22 so as to secure guide 21 to wall 22. Most typically, wall 22 is inwardly embossed at 28 so as to provide a space 29 which will receive the enlarged head of post 23. Usually a second wall 31 is mounted in abutting relation to wall 22 to complete the assembly, with the second wall advantageously providing an electromagnetic interference, EMI, shield. Second wall 31 also insures equipment is smooth. In some instances, outer wall 31 is not provided, and in still other embodiments, the inwardly embossed area 28 is not provided so that the post merely extends beyond wall 22.
One of the problems with such prior art card guide mounting schemes is that enlarged head 27 on post 23 can be sheered off during insertion of the post through opening 24, which is often punched in sheet metal that usually is employed as wall 22. Thus, the card guide will no longer be positively held in hole 24 by a barb or enlarged post head, and the guide is free to back out of the hole, for example, during an attempted assembly of the printed circuit board into the guide. As will be understood, printed circuit board 32 is held at an opposite side thereof by a similar, oppositely facing, card guide (not shown), with the printed circuit board being slid longitudinally along the pair of card guides during fabrication of the electronic assembly. As also can be seen from FIG. 1, the distance or width, W, between the outside edge of the card guide 21 and the inwardly facing surface of wall 22 is lost as far as being available for electronic components or pathways on printed circuit board 32. Since this lost area occurs on both edges of the printed circuit board and over the entire length of the board, there is an area, equal to twice this width dimension W times the length of the printed circuit board, that cannot be used for electronic circuitry as a result of the structure by which the printed circuit board or card 32 is held by prior art card guides.
Accordingly, it is an object of the present invention to provide a card guide for a printed circuit board, electronic component card or the like, which has an improved structure for mounting of the guide to a wall of an electronic housing or chassis and thus an improved structure for mounting the card inside the housing.
Another object of the present invention is to provide a printed circuit board mounting card guide which is more positively and reliably mounted to the wall or chassis of an electronic apparatus and which increases the usable area available for electronic components and pathways on the printed circuit board for any given width between opposed housing walls.
Still a further object of the present invention is to provide a card guide for printed circuit boards or the like which is easy to mount to an electronic equipment housing wall or chassis frame.
Still another object of the present invention is to provide a card guide for a printed circuit board or card which is easy and inexpensive to manufacture, can be installed without special tools, and is durable.
The card guide and electronic equipment housing assembly of the present invention have other objects and features of advantage which will become apparent from, and are set forth in more detail in, the accompanying drawings and the following description of the Best Mode of Carrying Out the Invention.